Acquired ornithine transcarbamylase deficiency in pediatric and adolescent patients with fibrolamellar hepatocellular carcinoma

Ornithine transcarbamylase deficiency (OTCD) disrupts the metabolic pathway responsible for converting nitrogenous waste to urea, allowing for excretion. When impaired, ammonia levels accumulate in the blood resulting in severe, sometimes life-threatening toxicities. Abnormalities of the urea cycle are often inherited, though there are some rarer acquired forms. We describe two cases of acquired OTCD in pediatric patients with fibrolamellar hepatocellular carcinoma (FL-HCC). We detail its presentation and management, explore potential underlying pathophysiology, and propose a practice change to optimize care of FL-HCC patients.